Optical technology offers the capability of transmitting a plurality of signals on a single fiber. As the use of optical technology increases, the number of signals transmitted on a signal fiber also increases. Currently, signals of four, eight, or sixteen different wavelengths are transmitted over a single fiber.
In order to transmit a large number of signals on a given cable, signals carried on a plurality wavelengths are multiplexed together for transmission. After the multiplexed, multi-channel signal reaches the destination, the signals are demultiplexed to access the information carried by a single channel. Conventional wavelength division multiplexers ("WDMs") are used to combine individual signals as well as separate a combination signal into individual wavelength signals.
To separate a combination signal into its components, conventional wavelength division multiplexers utilize a plurality filters cascaded in series to isolate each channel. Each filter passes light centered around a single wavelength. A filter is provided for each of the component wavelength. The output of each filter is the signal from a single wavelength. Thus, the signal is separated into its components.
Although such conventional systems can separate a signal into its components, a high insertion loss results. In the context of this application, the insertion loss is the loss for a particular component due to reflections in and transmission through the filters in a WDM. Each filter has a transmission loss as well as a reflection loss associated with it. As a result, the first component separated from the signal has the lowest insertion loss. The insertion loss increases for components separated from the signal later. This loss is highest for the last component isolated. The additional insertion loss further degrades the output signal for each component.
Accordingly, what is needed is a system and method for reducing the transmission loss associated with conventional wavelength division multiplexers. The present invention addresses such a need.